In the U.S., nearly 12.3 million specialty endoscopic procedures were performed in 2005. The U.S. market for specialty endoscopic surgery products—including those used in arthroscopic, endovascular, gastrointestinal, neurologic, otorhinolaryngologic, and thoracoscopic procedures was valued at approximately $1.7 billion in 2005. Growing at a compound annual rate of 9.3%, sales of these products are projected to reach an estimated $3.8 billion in the year 2014 (source: medtechinsight.com).
The advantages of endoscopic surgery over open surgery include lower overall treatment costs, reduced patient trauma, shorter hospital stays, and faster recovery times. These benefits have resulted in the conversion of many types of open surgery procedures to endoscopic procedures, a continuing trend that is being driven by advancements in the array of endoscopic surgery products that includes access devices, endoscopes, hand instruments, electrosurgery systems, and fluid management systems, among others.
Carpal tunnel is formed by an arch of the eight wrist bones, spanned on its palmar surface by the transverse carpal ligament, the flexor retinaculum. The carpal tunnel functions as a large mechanical pulley to provide the appropriate moment arms for the digital flexor tendons as they pass through the tunnel. The tendons can then transmit force out in to the fingers and impart only an appropriate amount of tension to develop torque at the level of the wrist.
Within the carpal tunnel these tendons are lubricated and nourished by two synovial membranes—the radial and ulnar bursa. The medial nerve also shares the carpal tunnel, and then branches out to provide sensory innovation to the palmar surfaces of the thumb, index, long and a portion of the ring finger. In addition, a small motor branch of the medial nerve supplies the thenar muscles, which are responsible for lifting the thumb in to opposition with the fingers.
Carpal tunnel syndrome describes numerous clinical signs and symptoms resulting from pressure on the medial nerve inside the carpal tunnel. The typical etiology is increased pressure within the carpal tunnel, which interferes with the function of the medial nerve. The patient experiences numbness and tingling in the fingers, together with pain that may radiate as far as shoulder or base of the neck. Other symptoms include: impaired grasping ability, due to sensory deprivation from the figures; loss of sleep from pain and numbness in the hand; and weakness or atrophy of the thenar muscles.
The pathology generally results from a swelling of the synovial membranes, which is often idiopathic. Carpal tunnel syndrome can also be caused by pressure on the medial nerve from rheumatoid arthritis or edema in the final trimester of pregnancy.
Many instances of carpal tunnel syndrome can be treated conservatively, typically with a resting split and cortisone injection in to the carpal tunnel. However if the symptoms persist and/or reoccur, or if the patient has a severe sensory deficit or loss of function in thenar muscles, then surgical decompression of the nerve by release of the transverse carpal ligament is often indicated.
Commonly practiced surgical procedure for decompression of carpal tunnel ligament is accomplished by a longitudinal incision paralleling the thenar crease. The incision is carried down through the skin, subcutaneous fat, and palmar fascia to avoid the palmaris brevis muscle and then the transverse carpal tunnel ligament. Although the carpal tunnel is inspected, most cases do not require any surgical treatment within the carpal tunnel, other than the division of the ligament. Thereafter, the skin is sutured and the patient is splinted for approximately three weeks. A typical surgery requires approximately 20-25 minutes, including the dressing, and is performed as an outpatient.
The endoscopic carpal tunnel release instrument as described in U.S. Pat. Nos. 4,963,147; 4,962,770; 5,089,000; 7,628,798, US 2010/0228275 and 5,306,284 are comprised of a probes with dissecting devices, and endoscope attached to a camera for visualization. The probe is inserted in to the carpal tunnel through a small incision in the wrist. The scope inside the probe visualizes the transverse carpal ligament. Once the probe is properly placed the blade is raised inside the carpal tunnel dissecting the transverse carpal ligament from inside. This will result in decompression of carpal tunnel. This technique is more advantageous due to small incision resulting less trauma to the patient and faster recovery.